Hazu (幡豆郡, Hazu-gun) was a district located in southeastern Aichi Prefecture, Japan.
As of 2003 (the last data available), the district had an estimated population of 58,921 with a density of 696.88 persons per km2.
Bordering on Mikawa Bay, one of its noted products was sharkskin and dried shark meat, which was sent as taxes to the Imperial household in Kyoto.
Modern Hazu District was created on 1 October 1889 as part of the cadastral reforms of the early Meiji period.
On 15 December 1953, Nishio was elevated to city status, annexing the towns of Hirasaku and Terazu and two villages later that year.